Understanding the scabbling of concrete using microwave energy

• Published in: Cement and concrete research Vol. 75; pp. 75 - 90
• Main Authors: Buttress, A.J., Jones, D.A., Dodds, C., Dimitrakis, G., Campbell, C.J., Dawson, A., Kingman, S.W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.09.2015
• Subjects: ARAMIDS; Brazil; Cements; Concrete; CONCRETE BLOCKS; CONCRETES; Controllability; Discs; DUSTS; Energy use; GHZ RANGE; Gravel; LIMESTONE; MATERIALS SCIENCE; MATERIALS TESTING; MECHANICAL PROPERTIES; Microwave processing; MICROWAVE RADIATION; Microwaves; Radioactive waste; SURFACE COATING; SURFACES; Radioactive waste; Concrete; Microwave processing
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2015.04.009

Concrete blocks supplied by the UK Sellafield nuclear site were treated with microwave energy using a 15kW system operating at 2.45GHz. The effect of aggregate type (Whinstone, Gravel and Limestone); standoff distance; and effect of surface coating were studied to determine their influence on the systems performance in terms of mass and area removal rates and evaluate the controllability of the process. All blocks were scabbled successfully, with mass and area removal rates averaging 11.3gs−1 and 3cms−1 respectively on treating large areas to a depth of 25mm. The use of a Kevlar barrier between the block and applicator was found to significantly reduce the generation of dust as only 1.6% of the scabbled mass was in the <106μm — that generally considered to be airborne. Importantly Brazilian disc testing of the scabbled block showed that the process did not adversely affect structural properties of the test blocks after treatment.